The 2023 dengue outbreak in Bangladesh was the worst ever recorded, with 277,801 cases and 1,393 deaths. About 52% of cases were outside Dhaka, and the male-to-female ratio was 3:2. The highest number of cases was among 19–29-year-olds (28.7%). The overall case fatality rate (CFR) was 0.5%, with the highest CFR among children aged 0–10 years (12%). Fever was the most common symptom, followed by joint pain. The 2023 outbreak had significantly higher odds of fatalities, cases, and hospitalizations compared to previous outbreaks (2008–2022). The outbreak started in January 2023 and spread rapidly across 64 districts, with Dhaka being the main epicenter. However, 63.4% of cases were outside Dhaka, with Chattogram and Barisal becoming hotspots. The outbreak started 7 months earlier than previous ones, leading to the highest number of cases and deaths in July and August 2023. The CFR was higher in females than males, and in the 30–39 age group, females had a 3-fold higher CFR than males. The outbreak's peak was in September with about 80,000 cases, and the peak is expected to last longer than previous outbreaks. The outbreak's characteristics, including rapid spread and higher CFR, suggest changes in dengue transmission. The study used statistical methods to analyze data from the national dengue surveillance system. The study has limitations, including underreporting due to hospital-based data and lack of seroprevalence data. The findings highlight the need for further research on dengue outbreaks in Bangladesh.The 2023 dengue outbreak in Bangladesh was the worst ever recorded, with 277,801 cases and 1,393 deaths. About 52% of cases were outside Dhaka, and the male-to-female ratio was 3:2. The highest number of cases was among 19–29-year-olds (28.7%). The overall case fatality rate (CFR) was 0.5%, with the highest CFR among children aged 0–10 years (12%). Fever was the most common symptom, followed by joint pain. The 2023 outbreak had significantly higher odds of fatalities, cases, and hospitalizations compared to previous outbreaks (2008–2022). The outbreak started in January 2023 and spread rapidly across 64 districts, with Dhaka being the main epicenter. However, 63.4% of cases were outside Dhaka, with Chattogram and Barisal becoming hotspots. The outbreak started 7 months earlier than previous ones, leading to the highest number of cases and deaths in July and August 2023. The CFR was higher in females than males, and in the 30–39 age group, females had a 3-fold higher CFR than males. The outbreak's peak was in September with about 80,000 cases, and the peak is expected to last longer than previous outbreaks. The outbreak's characteristics, including rapid spread and higher CFR, suggest changes in dengue transmission. The study used statistical methods to analyze data from the national dengue surveillance system. The study has limitations, including underreporting due to hospital-based data and lack of seroprevalence data. The findings highlight the need for further research on dengue outbreaks in Bangladesh.